Microelectronic devices, such as semiconductor devices and field emission displays, are typically fabricated on and/or in microelectronic workpieces using several different types of process machines (“tools”). A workpiece, for example, is often processed using tools for depositing, implanting, diffusing, doping, etching, polishing/planarizing, and patterning materials. A workpiece can typically undergo several processing steps within a single enclosed clean or “mini” environment within a processing tool. For example, microelectronic workpieces can be plated with a conductive material, annealed, etched, and cleaned, using a plurality of processing chambers all housed within a single processing enclosure that defines a clean mini environment.
These processes can be performed on each workpiece individually in separate single-wafer processing chambers, and the workpieces can be moved from one processing chamber to the next, a technique referred to in the industry as single wafer processing. One initial problem encountered with single wafer processing was determining how to deliver individual workpieces to and from the enclosure while maintaining a clean environment within the enclosure. One approach to addressing this problem has been to load several workpieces in a portable container while the container is in a clean environment and then seal the container with a removable door. Accordingly, the interior of the container can define another clean mini environment. The door is then removed when the container is flush with a hatch of the processing enclosure to reduce the likelihood for introducing contaminants into the enclosure.
One conventional container having the foregoing design is a Front Opening Unified Pod (FOUP). In operation, the door of the container is positioned flush against the hatch of the processing enclosure to reduce or eliminate any non-clean gas volume between the door and the hatch, and the door and the hatch are then moved together into the enclosure, allowing access between the interior of the container and the interior of the processing enclosure. A robot then retrieves individual microelectronic workpieces from the container, delivers them to the appropriate processing stations, and returns them to the container after they have been processed. Once the container has been refilled with processed microelectronic workpieces, the removable door is put back in place and the container is moved away from the enclosure.
To improve the efficiency of the foregoing operation, it may be desirable to place a relatively large number of microelectronic workpieces in a single container. It may also be desirable to increase the size of the microelectronic workpieces. Accordingly, the container can become quite heavy when fully loaded with microelectronic workpieces, making the container difficult to handle.
One known approach to addressing the foregoing problem (shown schematically in FIGS. 1A-B) is to provide a processing enclosure 10 with a container intake section 12 that allows containers 13 to be loaded at an ergonomically suitable height. The container 13 is translated horizontally at the intake section 12 (as indicated by arrow “T” in FIG. 1A) to align a removable door 16 of the container with a door remover of the enclosure 10. The door remover 18 can include a panel positioned in an aperture of a movable frame 14. The door remover 18 engages the door 16 and moves it horizontally into the enclosure, as indicated by arrow “U.” Referring to FIG. 1B, the frame 14 and the container 13 move upwardly together on an elevator 20 (as indicated by arrow “V”) to align the open container 13 with a robot 19. The elevator 20 then indexes the container 13 upwardly and downwardly (as indicated by arrow “W”) to align each microelectronic workpiece in the container 13 with the robot 19. The robot 19 transfers each workpiece to one or more processing chambers 21 for processing, and then returns each workpiece to the container 13.
One drawback with the approach shown in FIGS. 1A-B is that moving the container 13 up and down to align the workpieces with the robot 19 can cause the workpieces to shift within the container 13. As the workpieces shift, they can be damaged, or the workpieces can become misaligned relative to the robot 19. The robot 19 may then be unable to retrieve the workpieces from the container 13.
Another problem associated with moving microelectronic workpieces into and out of a container has been determining which positions within the container are occupied by workpieces, and whether the workpieces in the occupied positions are properly seated. One approach to addressing this problem, disclosed in U.S. Pat. No. 6,188,323 to Rosenquist et al., is to mount a scanning device on a door opener that opens the door of the container. The door opener operates by engaging the door of the container and retracting the door horizontally into the enclosure and then downwardly away from the container. As the door opener moves downwardly with the door, the scanner moves past the workpieces in the open container and scans the workpieces with a beam of light. However, this arrangement may not provide for consistent scanning results and, in some cases, the scanner can mistakenly indicate workpieces in unoccupied positions, and/or mistakenly indicate no workpieces in occupied positions.